spark plug hole stripped

like a moron i stripped the spark plug hole on my pa50. it's been on the verge for a while, but now it's really stripped.

any ideas on how to fix it?

Re: spark plug hole stripped

chuck russo va /

if the head is removeable just buy a used head off ebay or somthing

Re: spark plug hole stripped

I didn't want to say it, but I was thinking the only way would be a new head too---

if you used a tap & die, it wouldn't fit a plug---

Any thing you "Bodge" or "jury rig" will end up screwing your compression, I would think.

Re: spark plug hole stripped

> Any thing you "Bodge" or "jury rig" will end up screwing your

> compression, I would think.

so i'm screwed for now. i guess now is the time to upgrade to get a 70cc kit. any ideas on a quick temporary fix until then?

i'm not exactly mechanically inclined, so all the help i can get is appreciated.

Hacking, Jury rigging and bodging

*Disclaimer* Although I have owned 5 mopeds

(NC-50 Express 1978)

(Tomos Targa 2000)

(2 QT-50's 1982)

(Tomos Bullet, 1992)

the majority of my knowledge comes from reading the great posts. I'll have a lot more hands on experience soon--with the garage/shop.

That said, it would seem like you could put in a new plug (I'm assuming that's all you need to get done, right??) and somehow use JB-Weld or some other Epoxy/Metal type substance to use as a seal/gasket.....essentially making your plug and head a single unit....

I would be worried about getting that gunk into the engine though. i try to think: "What would the guys on Junkyard Wars do to fix this...?"

If you're going to be replacing it anyway, there must be some way to get a plug in there and secure/seal it without losing all the compression---

As per the disclaimer, this might be an absolutely stupid idea---You're the one who asked about "bodging" it.

McGuyver would get that moped going with one trip to the hardware store.

Fred's even better than Mcguyver, so there has to be a temporary fix.... until you get the upgrade.

Re: Hacking, Jury rigging and bodging

chuck russo va /

maybe weld a new plug in it, jb weld or epoxy should work also jyust make sure the plug is in there strait

Re: Hacking, Jury rigging and bodging

Matt Wilson /

GK you should be able to find a used one... since people who have made the 70cc upgrade will have an extra engine kicking around.

I'd mention the bike and year and search around for it. You could probably find one for $20.

If it was any other bolt I think the JB weld and epoxy would work, but because its under 100psi I think you will get a little leakage, and a big loss in performance.

Or look on the bright side, this is a great excuse to get a 70cc kit


Re: Hacking, Jury rigging and bodging

Matt Wilson /

But I suppose if you try epoxy or welding the only thing that you have to lose is a good spark plug.

It will or won't work, and if it doesn't you were planning on buying a new head anyways.


here ya go...

<a href=""></a>;

he says there if "your part isnt listed, email me"... probably has a cylinder head sitting in his garage.

good luck!


Re: spark plug hole stripped

why don't you do a search for "stripped spark plug" (or threads) ?

There are 2 good ways that could work.

A Heli-Coil or a 'thread insert"

Do a search for either one of those also.

I think the JB Weld is a waste of time... But I have been surprised before by the stuff.

But I wouldn't ride it farther than you'd want to push it.


thanks for your help everyone. i ended up removing the washer from the plug, and somehow that somewhat fixed it. i can tell that it's losing a little bit of compression, but it's rideable once again.

casey, what kit are you going to go with for your PA50?

Re: Fred: Question

I thought of the helicoil... but I didn't think it would hold compression--- do you think it would? I've never seen one, but I understand what it does...

Re: Fred: Question

Helicoils are used in cars for the same purpose. I bet any decent repair shop or automotive machine shop could hook you up on the cheap!

Re: Fred: Question

That sounds a lot better than using jb weld ----

that's for sure!

Re: VW S.O.P.

That was where I learned about Heli-Coils way back in the last century.

Stripped #3 on my '58 Bug, my first car. Took the engine out and the shop charged $10.00 to do it.

Of course this was way back in Ninetenn and Seventy Four, or so.

Use nothing less, or replace the head.


Re: VW S.O.P.

I recently stripped the threads on a Honda CT70 minitrail. I purchased a steel thread insert (not a helicoil) from the local hardware store. basically what you do is drill out the stripped threads to the correct new size indicated on the insert and then tap it out to the tap size also recommended. I did use JB Weld only to lock the threads in the new hole. this should work even better on you ped because you don't have valves to worry about. It has worked perfectly with no apparent loss of compression. All of the above was done with the head removed. personally I think this is a better alternative than purchasing an expensive new head. Also, I have not heard much positive commentary about the 70cc kits. Be VERY careful with that plug barely in the head. I have seen plugs fire out of the head with some dangerous velocity. Hope this helps!

listen to the good advise

The heli-coil is the way to go. They have been around for a long time and have been proven to be a very inexpensive and effective remedy for this problem. That is what the product was designed to do and it works...Ken D

Re: spark plug hole stripped

ItsLookingUp /

I had the same problem with a 1983 PA50-II I recently purchased. I purchased a replacement head from a local Honda dealer for about $60.00. It took a week to get in. Just an option.

Re: thanks

hey, i think im just going to go for the malossi 70cc kit, malossi 21mm carb, and malossi 16-32 transmission kit.

they have a 70cc water cooled kit liested, but he said its not in stock yet... if they get them in stock by the time im finished painting mine, i may get that... but its like 125$ more than the air cooled one...


Re: spark plug hole stripped

Ron Brown /

My 2 cents worth.

For stripped holes other than spark plugs, Helicoils are the way to go.

Because spark plug are removed and replaced so often, the one piece insert, mentioned elsewhere in this thread, with a shoulder to tighten up against is a better solution. I dont remember the brand name of these, but they are readily available at auto parts and hardware stores.

Down sides to helicoils are that the sealing surface between the head and the plug are reduced by the size of the helicoil, the coil can loosen and move in the hole as you change plugs and my all time favorite, which I saw last year, the inner turn of the helicoil extends into the combustion chamber where the head can no longer heat sink it. This coil then gets hot enough to glow like a glow plug and fire the mixture as soon as the transfer ports open.

It did not backfire through the carb because it had reed valves, but it really did a number on all the crankcase seals. I think the only reason it continued to run was it was a two cylinder.


Re: spark plug hole stripped

Ron Brown /

Btw, if a Helicoil is all you can find, it will make an acceptable repair. Use a little liquid thread lock on the helicoil outer surface and keep an eye on it whenever you remove the spark plug,


Re: spark plug hole stripped

> Btw, if a Helicoil is all you can find, it will make an

> acceptable repair. Use a little liquid thread lock on the

> helicoil outer surface and keep an eye on it whenever you

> remove the spark plug,

wow.. i'm amazed at the amount of help i get on here. it's almost like having real friends =)

i think i'll just go with an insert until i can buy a new head. i was dying for a ride yesterday so i used some teflon tape. it worked fine for the first few miles, then i lost compression. i just happened to break down at a bar, so i had a beer and called my wife for a ride. okay it wasn't a beer, it was hard lemonade, i'm a sissy.

thanks again for the help.

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